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splod67

6n2 polo cranking not starting - which relay?

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splod67

My 6n2 has a fuel pump / fuse / relay issue.

The car sat idle for a few years and the fuel went bad. Starting it would take 30 seconds of cranking if not started every day. I would dilute the bad fuel with new fuel.

Now I've registered the car and put a full tank of fuel in. The car went well for one trip and now won't start. It cranks but no firing. I suspect the pump has gone. It blew fuse #40 which I have replaced but with no joy.

With the ignition turned on, there's no voltage at the sending unit plug. There's also no voltage at fuse #40. I suspect the fuel pump brought down the fuse and the relay, but I'm guessing.

I looked at this post http://www.clubpolo.co.uk/forum/index.php?showtopic=342585 which says that the fuel relay is the top left one. But I have no relay at that position. I only have 19 and 410 on the top right, and 100 on the bottom. The Haynes manual doesn't have a wiring diagram for fuel delivery.

Any help with which relay is for the fuel pump would be most appreciated.

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splod67

ok, after extensive web search 410 looks like the fuel pump relay. Now need torx screw driver to get to it.

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splod67

I've got the 410 out but it's a complicated beast with 7 pins. I know which ones power the fuse and the pump, but to test with a volt meter there's 5 pins left to get right and I'm not sure of their polarity. Some are for things like "Crash Input" and "Door switch input".

So I just want to buy a 410 now but that's not easy. There's a 6N(1) being wrecked about 50km away in a big yard where you pull parts yourself. Anyone know if a 6N(1) has a 410 in it?

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splod67

Fuel pump out. Connected it straight to battery and it didn't spin. It just made sparks at the battery terminals like it's short circuited. That explains the blown fuse. Still not sure about the relay. Have to source a pump (ebay) and a relay (wrecker). Current problem: how to get the metal hose clip off the pump output hose.

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splod67

thanks for the diagrams. A problem is that photobucket has reduced the resolution to the point where I can barely read them. and the VW diagrams, from what I can tell don't really say whether an input like "Crash Input" or "Door" should be normally high or low, so it's hard to know the exact combination of inputs to the 410 that would let me test it. After a 150km round trip to a wrecker, I know that the 6N(1), Jetta, Golf and a few other VW models don't have a 410, or at least the ones I saw didn't. Next, same length trip after a phone call to see if a 6N2 I found after more web searching has it's 410.

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PoloD

Lots on eBay!

Type in "410 VW relay".

Seems cheaper than 150km of fuel. Or indeed VW parts department on Monday.

PoloD.

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nige8021

Here's an enlarged version of the pump control diagram

post-36925-0-09863800-1438525486_thumb.j

The only input to the relay I can't find a definite answer to is the signal from the airbag on pin 3 of the relay, I would make an assumption that it's a Positive 12v pulse?? as in the event of a crash it also signals all the doors to unlock and that requires a Positive pulse to the locking pump unit

The "Door open" signal is there to momentary energise the fuel pump to prime the fuel lines, so it makes starting quicker as there will be a good pressure in the injector fuel rail

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splod67

I saw the 410s on ebay and they're cheap for UK residents but postage to Sydney is horrendous (20 pounds / AU$42) and a long wait. I've found one in Adelaide which should get here quicker and cheaper.

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